1. Field of the Invention
This invention relates to a method and apparatus for deflashing a fiber reinforced plastic article. More particularly, this invention relates to a deflashing method and apparatus for molded plastic articles reinforced with fibers which would remain as whiskers in the flash area if the articles were deflashed utilizing prior art techniques.
2. The Prior Art
When articles are molded from thermosets, thermoplastics, rubber and the like, the initial product often has extra material called "flash" attached along the mold parting line. Flash results from that portion of the charge which flows from or is extruded from the mold cavity during molding, and is undesirable on most final products.
The removal of flash, or "deflashing", has been accomplished in many ways, e.g., manual deflashing with razor blades, rotation or shaking with abrasive media to break off the flash, and cryogenic deflashing. In the latter, flash is cryogenically embrittled followed by impact with deflashing media, such as pelletized steel or plastic shot, and/or tumbling. Various types of cryogenic deflashing apparatus are taught by U.S. Pat. Nos. 3 827 186 to Ehnot, 3 909 988 to Kerwin et al., 4 312 156 to McWhorter and 4 519 812 Brull et al., all of which are hereby incorporated by reference.
Deflashing has been complicated by the inclusion of some types of reinforcing staple fibers in charges (compounds) to be molded. When polyester staple fibers are added, the flash itself can be removed, but the molded part is left with polyester fiber whiskers/tendrils protruding at the parting line in the original area of flash. This is not a problem with fiber glass reinforced plastic parts, since fiber glass easily breaks away during deflashing.
The present invention has been developed to overcome the problem of fiber whiskers protruding from the plastic part after using prior art deflashing techniques.